[dpdk-dev] [PATCH] doc: rename guidelines for contributors

[Thomas Monjalon]

> > Clarify target of guidelines by renaming the title and the directory.
> > 
> > Signed-off-by: Thomas Monjalon <thomas.monjalon at 6wind.com>
> 
> Acked-by: John McNamara <john.mcnamara at intel.com>

Applied